1. Field of the Invention
The present invention relates to a failure determining apparatus of a gas-insulated electrical appliance, which determines presence or absence of ground-fault or short-circuit of a charged conductor in a gas section, by detecting a change in the gas pressure in the gas section forming the gas-insulated electrical appliance.
2. Description of the Related Art
A gas-insulated electrical appliance has a cylindrical metal container housing therein a charged conductor corresponding to a single phase or three phases. The former has a risk of suffering from a ground-fault of the charged conductor to the metal container, and the latter, ground-fault of charged conductor of each phase to the metal container and short-circuit between the charged conductors of different phases. Since these inconveniences are similarly covered by the present invention, only the former case will herein be described.
A conventional failure determining apparatus of a gas-insulated electrical appliance will first be described with reference to the drawings. FIG. 17 illustrates the configuration of the conventional failure determining apparatus of a gas-insulated electrical appliance.
In FIG. 17, 1 represents a cylindrical metal container to be filled with an insulating gas; 2, a charged conductor housed in the metal container 1; and 3a, 3b and 3c, insulating spacers partitioning the metal container 1 into gas sections and insulation-supporting the charged conductor 2.
Also in FIG. 17, 11 represents a gas pressure detector detecting a gas pressure signal corresponding to a gas pressure of a gas section for comprehensive control through communicating piping, attached to the metal container 1; 12, a sampling circuit sampling a gas pressure signal issued by the gas pressure detector 11 after the lapse of a prescribed period of time by input of a ground-fault current detection signal from outside; 13, a failure determining circuit which determines occurrence of a ground-fault if a sampled gas pressure is larger than a threshold value through comparison of the gas pressure signal sampled at the sampling circuit 12 and the threshold value.
Operations of the conventional failure determining apparatus of a gas-insulated electrical appliance will now be described with reference to the drawings. FIG. 18 is a waveform diagram showing a gas pressure signal detected by the gas pressure detector of the conventional failure determining apparatus of a gas-insulated electrical appliance.
For one of the gas sections formed by partitioning the metal container 1 by means of insulating spacers 3a and 3b under comprehensive control through a communicating piping, when a ground-fault occurs between the charged conductor 2 and the metal container 1, the pressure of the insulating as in this gas section suddenly increases near the arc, leading to production of a pressure wave. The gas pressure detector 11 detects a gas pressure signal based on superposition of a gas dynamic pressure signal corresponding to a dynamic pressure of the insulating gas of this pressure wave on a gas state pressure signal corresponding to the static pressure of an auxiliary gas filling the neighboring gas section connected by the communicating piping.
This gas pressure signal and a ground-fault current detection signal from outside after the lapse of a prescribed period of time from the occurrence of the ground-fault are entered into the sampling circuit 12. Therefore, the gas pressure signal P2 at the point in time T2 when a prescribed period of time t from the point in time T1 when this ground-fault current detection signal has been entered is sampled (see FIG. 18).
In the failure determining circuit 13, occurrence of a ground-fault is determined if the sampled gas pressure signal P2 is larger (the gas pressure signal P2 is larger in FIG. 18).
Although not shown in FIG. 17, the gas pressure detector 11 is attached to the metal container 1, also for the other gas sections, to determine occurrence of a ground fault by connecting the same to the sampling circuit and the failure determining circuit.
In the conventional failure determining apparatus of a gas-insulated electrical appliance, as described above, the gas pressure signal P2 is sampled at the point in time T2 upon the lapse of the prescribed period of time t from the point in time T1 of input of the ground-fault current detection signal, on the assumption that the gas pressure signal detecting by the gas pressure detector 11 takes substantially the shape shown in FIG. 18. The sampled signal is compared with a prescribed threshold value Pt, and if the gas pressure signal P2 is larger, occurrence of a ground-fault is determined. However, the increase in gas pressure may differ from that shown in FIG. 18 under the effect of the size of the metal container 1 arranged between the insulating spacers 3a and 3b, the arc energy upon occurrence of the ground-fault, or the duration of the ground-fault. Because a threshold value cannot be primarily set, a problem is encountered in that the presence of occurrence of a ground-fault cannot accurately be determined.
The present invention was developed to solve the above-mentioned problems, and has an object to provide a failure determining apparatus of a gas-insulated electrical appliance, which permits improvement of certainty of determination through a combination of sensors of different types for the purpose of accurately identifying a gas section in which a ground-fault occurs without being affected by conditions upon occurrence of the ground-fault such as structural restrictions including the interval between the insulating spacers, the arc energy produced upon occurrence of the ground-fault, and the duration, thus permitting reduction of the trouble eliminating operations upon occurrence of an accident.
The failure determining apparatus of a gas-insulated electrical appliance of a first aspect of the present invention determining a failure, having a cylindrical metal container, a charged conductor housed in the metal container filled with an insulating gas, and a plurality of insulating spacers insulation-supporting the charged conductor from the metal container and partitioning the interior of the metal container into gas sections, comprises a high-speed developing sensor which detects a high-speed phenomenon caused by a failure such as a ground-fault or a short-circuit within the gas sections; a first failure determining circuit which determines the presence of a failure from an output of the high-speed developing sensor; a low-speed developing sensor which detects a low-speed phenomenon caused by a failure such as a ground-fault or a short-circuit within the gas sections; a second failure determining circuit which determines the presence of a failure from an output of the low-speed developing sensor; and an arithmetic control circuit which identifies a gas section of the metal container in which a failure occurs from an output of the first and second failure determining circuits.
The failure determining apparatus of a gas-insulated electrical appliance determining a failure of a second aspect of the invention, having a cylindrical metal container, a charged conductor housed in the metal container filled with an insulating gas, and a plurality of insulating spacers insulation-supporting the charged conductor from the metal container and partitioning the interior of the metal container into gas sections, comprises a gas pressure detector which detects a change in the gas pressure of the gas sections; a first sampling circuit which fetches a change in the gas pressure from the gas pressure detector on the basis of a failure current detection signal; a failure determining circuit which determines an accident occurring gas section when a change in gas pressure fetched by the first sampling circuit is over a first threshold value; a decomposed gas detector which performs detection by ionizing a decomposed gas of the gas section; a second sampling circuit which fetches a decomposed gas concentration from the decomposed gas detector; a second failure determining circuit which determines an accident occurring gas section when a decomposed gas concentration fetched by the second sampling circuit is over a second threshold value; and an arithmetic control circuit which determines occurrence of a failure in the gas section of the metal container when a decomposed gas exceeding the second threshold value occurs within a gas section in which an increase in pressure of over the first threshold value occurs, on the basis of output of determination of the first and second failure determining circuits.
The failure determining apparatus of a gas-insulated electrical appliance determining a failure of a third aspect of the invention, having a cylindrical metal container, a charged conductor housed in the metal container filled with an insulating gas, and a plurality of insulating spacers insulation-supporting the charged conductor from the metal container and partitioning the interior of the metal container into gas sections, comprises an impact gas pressure detector which detects an impact gas pressure of the gas section; a relay circuit which incorporates an operation signal of the impact gas pressure detector; a decomposed gas detector which performs detection by ionizing a decomposed gas in the gas section; a sampling circuit which fetches a decomposed gas concentration from the decomposed gas detector; a failure determining circuit which determines an accident occurring gas section when a decomposed gas concentration fetched by the sampling circuit is over a prescribed threshold value; and an arithmetic control circuit which determines occurrence of a failure in a gas section of the metal container when there occurs a decomposed gas exceeding the prescribed threshold value within the gas section for which the impact gas pressure detector has operated on the basis of an output of the relay circuit and the failure determining circuit.
The failure determining apparatus of a gas-insulated electrical appliance determining a failure of the fourth aspect of the invention, having a cylindrical metal container, a charged conductor housed in the metal container filled with an insulating gas, and a plurality of insulating spacers insulation-supporting the charged conductor from the metal container and partitioning the interior of the metal container into gas sections, comprises a photo-sensor which detects an arc light leaking upon occurrence of a failure in the gas section; a relay circuit which incorporates an operation signal of the photo-sensor; a decomposed gas detector which performs detection by ionizing a decomposed gas of the gas section; a sampling circuit which fetches a decomposed gas concentration from the decomposed gas detector; a failure determining circuit which determines an accident occurring gas section when a decomposed gas concentration fetched by the sampling circuit is over a prescribed threshold value; and an arithmetic control circuit which determines occurrence of a failure in a gas section of the metal container when there occurs a decomposed gas of over the prescribed threshold value within a gas section in which the photo-sensor has operated, on the basis of an output of the relay circuit and the failure determining circuit.
The failure determining apparatus of a gas-insulated electrical appliance of the second aspect of the invention may further comprises a photo-sensor which detects an arc light leaking upon occurrence of a failure in the gas section; and a relay circuit which incorporates an operation signal of the photo-sensor; wherein the arithmetic control circuit determines occurrence of a failure in a gas section of the metal container when a decomposed gas of over the second threshold value occurs in a gas section in which a pressure increase of over the first threshold value has occurred, and the gas section agrees with the gas section for which the photo-sensor has operated.
In this failure determining apparatus of a gas-insulated electrical appliance, the arithmetic control circuit preferably controls the sampling circuit so as to obtain an output of the decomposed gas detector only for a gas section on the basis of the gas section information sensed by the photo-sensor.
In the failure determining apparatus of a gas-insulated electrical appliance of the second aspect of the invention, the arithmetic control circuit preferably controls the second sampling circuit so as to obtain an output of the decomposed gas detector only for a gas section on the basis of gas section information as determined by the gas pressure detector.
In the failure determining apparatus of a gas-insulated electrical appliance of the third aspect of the invention, the arithmetic control circuit preferably controls the second sampling circuit so as to obtain an output of the decomposed gas detector only for a gas section on the basis of gas section information as determined by the gas pressure detector.
In the failure determining apparatus of a gas-insulated electrical appliance of the fourth aspect of the invention, the arithmetic control circuit preferably controls the sampling circuit so as to obtain an output of the decomposed gas detector only for a gas section on the basis of the gas section information sensed by the photo-sensor.
The failure determining apparatus of a gas-insulated electrical appliance determining a failure of the fifth aspect of the invention, having a metal container, a charged conductor housed in the metal container filled with an insulating gas, and a plurality of insulating spacers insulation-supporting the charged conductor from the metal container and partitioning the interior of the metal container into gas sections, comprises a gas pressure detector which detects the gas pressure of the gas section; a first failure determining circuit which determines an accident occurring gas section when an output of the gas pressure detector is over a first threshold value; a decomposed gas detector which detects a decomposed gas of the gas section; a second failure determining circuit which determines an accident occurring gas section when an output of the decomposed gas detector is over a second threshold value; and an arithmetic control circuit which determines occurrence of a failure in the gas section of the metal container when a decomposed gas exceeding the second threshold value occurs within a gas section in which an increase in pressure of over the first threshold value occurs, on the basis of output of determination of the first and second failure determining circuits; wherein the detectors are arranged in a single gas piping system derived from the gas section.
In the failure determining apparatus of a gas-insulated electrical appliance of the fifth aspect of the invention, the detectors are preferably arranged in a single gas piping system derived from the gas section.
The failure determining apparatus of a gas-insulated electrical appliance of a fifth aspect of the invention may further comprises a detector mounting block made of an insulator having therein a gas piping branching from a gas piping; a gas pressure detector and a decomposed gas detector attached to the branch gas piping of the mounting block, respectively; and a case secured to the block, covering these detectors.
The failure determining apparatus of a gas-insulated electrical appliance of a fifth aspect of the invention may further comprises a block having therein a gas piping branching from a gas piping; a gas pressure detector and a decomposed gas detector attached to the branch gas piping of the block; and a case secured to the block, covering these detectors.
The failure determining apparatus of a gas-insulated electrical appliance of as fifth aspect of the invention may further comprises a temperature detector detecting the temperature of the insulating gas of a gas section mounted in the decomposed gas detector.